Best free program for installing windows with usb stick is Novicorp WinToFlash Lite.
Again, it’s not free but it’s free licence gives you all what you need for installing windows 7/8 or 10 via usb stick.
Procedure is exactly the same for all 3 version of windows and I will of course in this example show you how to put windows 7 64bit version on your usb drive.
First thing’s first, you can locate program here
I use this WinToFlash Lite version (just click that big red button “Lite edition Setup Download “).
When you download program insert you usb stick in computer(make sure you save all important stuff from it because program will format it), then run program and click next, next, install, finish, next, check “I accept EULA” and uncheck “I agree to send statistical information”, choose “Free Licence” and click next, next, select windows setup bootable USB wizzard, check “always start in wizzard mode” and click next, choose “I have CD inserted” and click next, press select to choose where is your windows cd location, locate it and select it(in my example it’s DVD RW Drive E:), select it and press ok and one more time click next and on next screen press “continue”(leave CAPTCHA off, don’t turn it on or you will always have to answer annoying questions), choose “I do accept the terms of the licence agreement and click “continue”, that’s it, wait program to finish(it takes about 10-15 min max), when finished just press “Exit” and that’s it, you have your first bootable windows 7 installation.
It’s same procedure for any other windows just insert correct dvd in your computer DVD drive. Now all you have to do is make sure your first boot device on you computer is USB(suggestion, if you have more usb ports avoid putting usb flash drive in “blue” usb port because it’s USB 3.0 port and you can’t install Windows 7 this way, via that port.